FIG. 1 shows a fuel injector known from the related art, having a conventional three-part design of an internal metallic flow guide part and a housing component. This internal valve tube is formed by an inlet connecting piece forming an internal pole, a non-magnetic intermediate part and a valve seat carrier accommodating a valve seat and is elucidated in greater detail in the description of FIG. 1.
German Patent Application No. DE 44 21 935 describes such an electromagnetically operatable valve in the form of a fuel injector. The internal valve tube forms the basic skeleton of the entire injector and has an essential supporting function in its entirety for the three individual components. The non-magnetic intermediate part is tightly and fixedly connected to both the inlet connecting piece and the valve seat carrier by welds. The windings of a solenoid are inserted into a plastic coil carrier, which in turn surrounds in the circumferential direction a part of the inlet connecting piece used as an internal pole and also surrounds the intermediate part. A wedge-shaped surface which is variably manufacturable according to a magnetic and hydraulic optimum is provided prior to applying a wear-resistant layer on the mutually contacting components of armature and/or internal pole.
The annular contact section formed by the wedge shape has a defined contact surface width, which remains largely constant over its entire service life because contact surface wear in long-term operation does not result in an enlargement of the contact width. The axially movable armature is guided by an internal guide surface of the intermediate part.